1. Technical Field
This description relates to active handoffs in a network.
2. Background
Cellular wireless communications systems, for example, are designed to serve many access terminals distributed over a large geographic area by dividing the area into regions called “cells”. At or near the center of each cell, a network-side access device (e.g., an access point) is located to serve client-side access devices located in the cell and commonly referred to as “access terminals” or “mobile stations.”
Examples of access terminals include cellular telephones, laptops, and PDAs. An access point generally establishes a call, also referred to as a “connection,” with an access point to communicate with other entities (e.g., servers in the internet or other users in the network).
A handoff refers to the process of transferring an ongoing call from one network-side access device to another. An ongoing call may be referred to as a “connection” or a “session,” both of which can be used interchangeably. A handoff may occur when an access terminal moves from the area covered by a first access point (with which it has established a call) to an area covered by a second access point. In this case, the handoff transfers the call from the first access point to the second access point to avoid call termination when the access point moves outside of the range of the first access point. A handoff may also occur when the capacity for connecting new calls of a particular access point is reached. In this scenario, the access point may transfer an existing call (or a new call) to another access point located within an overlapping cell.